In known high-voltage systems, surge arresters can be used to dissipate unacceptable overvoltages to ground. Surge arresters such as these can include a varistor which has a high impedance at relatively low voltages, but which starts to conduct at unacceptable overvoltages, and is thus able to limit the overvoltage.
During a test phase, a test voltage can be connected to the system and a check is carried out to determine whether the system can withstand this voltage. In this case, care must be taken to verify that a surge arrester which is connected to the high-voltage system does not respond to the test voltage, because it could otherwise limit the test voltage, or could be damaged by the test voltage. Surge arresters are therefore normally removed during the test phase.
Particularly in the case of gas-insulated fittings, in which the high-voltage systems and the surge arresters are gas-insulated, removal of the surge arrester in order to carry out an overvoltage test is, however, extremely complex.